The tremendous increase in utilization of computers and mobile terminals in the representation of documents has established a development of applications for displaying the documents in terminal devices. In addition to the development of viewer applications for terminal devices one area of development is preparation of documents, and especially content of the documents, applicable for storing, delivery and displaying in the terminal devices.
The preparation of the content of a document relates to rendering of document content for online previewing and viewing purposes. The goal is to find optimal rendering mechanism and viewing format satisfying limitations regarding storage of prepared content, delivery of the content to terminal device and displaying the content with satisfying accuracy. Moreover, there is need to provide textual content in the terminal device so that it cannot be copied, which then enables the copyright protection to such material wherein it is needed. For viewing purposes so called compressed raster images are the easiest way to ensure accurate visual output, and viewing them in the terminal device requires only image decompression and displaying capabilities available practically in every terminal device nowadays. However, due to different use cases of documents, and related functions such as zooming of content, and different terminal screen sizes there often is need to prepare multiple raster images with variety of resolutions in order to satisfy all requirements. This, in turn, increases need of storage capacity for storing the different versions of prepared raster images. In practice, this is extremely challenging to arrange especially in cases where millions of documents need to be prepared in the described manner for previewing and viewing purposes. This is especially true in systems with large user base wherein simultaneous preparation, distribution and delivery of content to terminal devices must be arranged to be sufficiently fast in order to provide good end user experiences.
Therefore, there is need to find and introduce a solution which solves the problem of balancing high quality output with minimal storage requirements.